The use of polymer encapsulated powders to make various magnetic circuit elements is well known in the art For example, in U.S. Pat. No. 5,004,577 to Ward, assigned to the assignee of the present invention and issued on Apr. 2, 1991, polymer encapsulated iron powder is utilized in the manufacture of a motor frame. Polymer encapsulated powders have also been utilized in the manufacture of permanent magnets. As noted in the Ward patent, the encapsulant may be a thermoplastic material, and the parts may be formed by injection of preheated powder material or by compaction of powder material in a preheated die or mold.
It would be desirable to provide a simple method for production of rotors and frames for permanent magnet type dynamoelectric devices using these encapsulated magnetic powders, which method would be suitable to high volume production conditions. It would be further desirable if such a method enabled the production of various components of permanent magnet dynamoelectric devices, with a minimum of process steps and wherein the size and location of the ferromagnetic and permanent magnet regions within the devices could be easily varied.